08-16-2013, 01:10 AM
Marty,
A lot of unnecessary effort there, unless you just want to use it as a teaching tool.
First thing you want to do is to check all the resistors in the LO circuit and replace any that are out of tolerance. This is assuming that you have already replaced all the paper caps in the radio.
Next, remove the oscillator coil and inspect it for broken wires, corrosion, etc. Oscillator coils generally go open due to corrosion on the feedback side of the coil. This is pretty easy to rewind, as a rule. Or you can have someone else rewind it for you.
Also, try subbing in a new tube, as a weak or gassy tube my fail to oscillate while still being able to pass some RF through it.
Another fun thing you can do to test whether the circuit is working as a first detector is to feed in a signal from a generator into the oscillator section (chassis ground and the LO section of the tuner is a good injection point). Choose a strong local station, add 460 KHz to their frequency, and inject that. Tune the tuner to their frequency on the dial, you should hear the station.
A lot of unnecessary effort there, unless you just want to use it as a teaching tool.
First thing you want to do is to check all the resistors in the LO circuit and replace any that are out of tolerance. This is assuming that you have already replaced all the paper caps in the radio.
Next, remove the oscillator coil and inspect it for broken wires, corrosion, etc. Oscillator coils generally go open due to corrosion on the feedback side of the coil. This is pretty easy to rewind, as a rule. Or you can have someone else rewind it for you.
Also, try subbing in a new tube, as a weak or gassy tube my fail to oscillate while still being able to pass some RF through it.
Another fun thing you can do to test whether the circuit is working as a first detector is to feed in a signal from a generator into the oscillator section (chassis ground and the LO section of the tuner is a good injection point). Choose a strong local station, add 460 KHz to their frequency, and inject that. Tune the tuner to their frequency on the dial, you should hear the station.
